Biopolymer alternatives to synthetic polymers are of substantial interest. Sustainable produced biodegradable polymers from renewable resources provide an important technological development required for environmental sustainability of a wide range of products currently made from synthetic polymers.
A variety of natural materials have been investigated for creating biopolymer materials, including poly lactic acid, soy protein, starch, chitin, and other natural structural materials. However, problems persist with biopolymer materials, including sustainability of the material source if it is diverting potential food crops to non food uses, physical properties in particular when wet, and ability to be processed using industrial processes analogous to those used in the synthetic polymer industry.
Keratin in its natural form displays the desirable robustness often sought from synthetic polymers, but it has not been possible to manipulate keratins in a useful manner to create alternatives to synthetic polymer materials as it is not naturally thermoplastic or formable. One reason for the robustness of keratins when compared to other natural materials is the high proportion of fibrous proteins occurring in keratin materials such as horns, hooves, hair, wool, feathers and nails. The highly ordered nature of this fibrous protein, in addition to the tendency of this protein to organize into fibrous structures, are important factors in keratins being very well suited to the creation of biopolymer materials.
Previous ways of isolating keratin from natural sources have rendered materials that are promising but not practically useful in creating robust materials capable of being processed in industrially acceptable means.
A common approach to form reconstituted materials from keratin involves blending of keratin with other polymers either using solvent casting or melt processing. Blended polymers are frequently not fully biopolymeric materials and so less than ideal from a sustainability perspective, in addition they may have inadequate physical performance arising from incomplete mixing of the components. Some materials have been constructed from pure keratins by casting materials from a variety of solvents, most commonly aqueous based. In these cases the form of the cast materials is limited. Films and fibres are much easier to create using these processes than larger volume or substantially thicker materials. In addition these materials often posses inadequate physical properties in particular when exposed to water.